With spin torque MRAM devices, spin polarized electrons are used to switch the orientation of magnetic layers. The amount of current needed to write spin torque MRAM is however high, and therefore not practical for some applications.
Proposed solutions have involved using the spin hall effect to generate spin current. With the spin hall effect, the spin current is generated in a transverse direction while a charge current flows in a longitudinal direction. While the spin hall effect can provide an effective mechanism for writing spin torque MRAM, these proposed devices employ three terminals where the tunneling current across the magnetic tunnel junction and the current that generates the spin hall effect torque are applied across different pairs of terminals. This requires two transistors per unit cell, thus increasing the cell area.
Thus, improved spin torque MRAM devices would be desirable.